Atrial flutter can cause false-positive ***ACUTE MI SUSPECTED*** interpretive statements

I first heard about this issue a couple of years ago in a webinar at the D2B Alliance website. Since then I have seen it several times in my own EMS system.

I also mentioned it when I commented on:

Review of Factors Associated With False-Positive Emergency Medical Services Triage for Percutaneous Coronary Intervention

According to that study the most common factors associated with false positives statements were:

  • A specific brand of one of three monitors used in the system
  • Sinus tachycardia
  • Missing lead recording on 12-lead printout
  • Atrial fibrillation
  • Female gender
  • Poor ECG baseline
  • A discussion ensues during

The authors make this important statement:

“Poor ECG baseline and failure to record all 12 leads for machine algorithm interpretation are false-positive associated variables that can be addressed by improved quality in field acquisition of 12-leads.”

It can’t be said often enough! That’s why I’m always harping on achieving excellent data quality!

The authors continue:

“Variables more difficult to address are sinus tachycardia and atrial fibrillation, which had a tendency to be wrongly interpreted by machine algorithm as acute MI.”

In response to that statement I made this comment:

“It would be interesting to know if they are including atrial flutter in with atrial fibrillation. Either way the message is clear. The specificity of the computerized interpretive algorithms is highest when a tachycardia is not present.”

The reason I questioned whether or not atrial flutter was included with atrial fibrillation is simple. Many times I have seen atrial flutter trigger a false-positive ***ACUTE MI SUSPECTED*** message on the LP12 but I can’t think of a time atrial fibrillation cause a false-positive statement (when poor data quality was not present).

Consider these cases that occurred in the past week.

Case #1

In this case the paramedic immediately realized the ***ACUTE MI SUSPECTED*** message was being caused by underlying atrial flutter. A “STEMI Alert” was not called from the field and the patient was not sent to the cath lab.

Case #2

This case was a little more difficult because 2:1 atrial flutter more difficult to recognize than 4:1 atrial flutter. It also must be said that this patient was “sicker” and presented very much like ACS. A “STEMI Alert” was called from the field and the patient ended up in the cath lab. No significant lesions were noted with angiography.

The point isn’t to blame the paramedic from the second case. A board certified emergency physician and a cardiologist both had to agree that this patient needed emergent angiography.

It’s easy to criticize individual paramedics especially when they’re from other EMS systems. What’s hard is to create quality improvement feedback mechanisms so that every call can be a learning opportunity.

There are two kinds of EMS systems in this world: those that make mistakes and those that have no idea whether or not they make mistakes (unless they receive a complaint).

Strive to be the former because anyone can be the latter.

5 Comments

  • Christopher says:

    Second ECG is tough! Rate and p-axis in II/III can lead you to 2:1 flutter. Also the T-waves are certainly strange looking. I think the only thing holding me back from a STEMI call is the rate on that one.

  • Christopher says:

    Another thing that a-fib/flutter can mess with is synchronized cardioversion. Resuscitation recently had a case where an ED used a Philips MRx set to sync through the pads and the R-wave detection kept picking up the fib/flutter waves as well, delivered a shock, caused R-on-T, v-fib…and thankfully a successful resuscitation.

    Sodeck GH, Huber J, Stöllberger C. Electrical cardioversion – misinterpretation of the R-wave. Resuscitation. 2011 Jan;82(1):135-6.

  • Mike Sherriff says:

    I too have had 2:1 A-Flutter read incorrectly as STEMI, on a Zoll.

  • speaking of a-flutter, when i review ekgs i’ve noticed the LP12s love to interpret VT as a-flutter.

  • Banery says:

    There always you want to a 740 problem during the installation.
    The MAC compatibility means that that Dub Turbo software
    can be powered by an iPad.

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EMS 12-Lead

Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation
Comments
Brooks Walsh MD
“Bad heartburn” – 82 y.o. female without chest pain.
The option was indeed turned on! As for non-CP presentations of ACS, I absolutely believe that these warrant the same level of urgency as the "typical" presentations. Both men and women, young and old, all commonly present without classic chest pain. Besides, how much difference is there between "burning in the epigastrium," and "pain in…
2014-08-21 17:10:37
Austin
“Bad heartburn” – 82 y.o. female without chest pain.
You took the words right off of my keyboard, Jason! A little bit of critical thinking works wonders when faced with "protocol versus best interests of the patient" type decisions. Not to encourage deviation from protocols and such, but it is a much less severe trespass if you bend the rules a bit as long…
2014-08-21 16:33:27
Brooks Walsh MD
“Bad heartburn” – 82 y.o. female without chest pain.
My uninformed opinion? I pretty much agree with AHA - if they aren't hypoxic, no need. I'm not sure how terrible superoxia really is, short-term, but why bother if it doesn't help?
2014-08-21 16:31:05
jason
“Bad heartburn” – 82 y.o. female without chest pain.
Chris Watford- as you probably know the "acute MI suspected" detection function in the LP12/15 is a programable option. I suspect the software didn't miss this but rather it wasn't turned on. As for treatment everyone has pretty much got it down. Finally as for activation. Absolutely! Don't real care if the protocol allows for…
2014-08-21 16:30:34
Austin
“Bad heartburn” – 82 y.o. female without chest pain.
There's not much I think I can add at this point, but I will comment on a couple of things. The reciprocal changes indicate to me that there is likely RCA involvement. Also, I've recently been hearing quite a bit about withholding O2 in ACS patients like this. Dr. Walsh, do you have any opinions…
2014-08-21 16:23:21

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